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Transcript
How do we see inside the Earth? • • • • • What do we use? __________________________ Seismology ____________________________ What do we know that produces seismic waves? P-waves “P” or Primary waves – – – – _______________ _______________ _______________ Travel through all mediums ( solid, liquid and air) “S” Waves • “S” or Secondary waves – – – – _______________ Vibrate ____________/ ____________ _____________ than “P” waves Only travel through _______________ The Crust • • • • • • ________ __________ Like an eggshell ___________ ___________ Can crack Two regions: – ______________ (Basalt rock) – ______________ (granite rock) • Crust is _______ dense than the mantle • Like ice on water; the crust _____________ on the mantle The Mantle • _____________ • Like the crust – __________ – __________ • Iron, magnesium, calcium are heavier elements • Mantle is ________ dense • How does the Earth’s crust add to the density of the mantle? • __________ ___________ down on the mantle…it compresses the minerals, increasing the pressure and squeezing them into rocks. The Mantle • • • • Higher temperature Why? __________ __________ Decay of radioactive elements Layers of The Mantle • Upper mantle • ___________ – Rigid rock upper portion of upper mantle • ___________ – Lies beneath lithosphere and “__________” like plastic – It is ________…silly putty • Lower mantle The Core • ________ layers: inner and outer core • ____ Earth’s volume • ____ Earth’s mass • 2x as dense as the Earth’s mantle • Why? • Made of _____ ______ • Inner core is VERY hot! • Some places as hot as the surface of the sun! • ______ ______ The Inner Core – How? – __________ from Earth keeps Iron packed tightly; doesn’t allow it’s atoms to ______ The Outer Core • Outer Core – _______ Iron – _______ pressure – _____ and _____ as Earth rotates – Creates _______ _________ – Affects Earth’s ________ – Produces _______ ______ – Possibly responsible for Earth’s magnetic field Convection Currents • What are convection currents? • ________ of heat flows from ______ to ______ • This sets up a convection current in the ________ Effects of Convection Currents • When the current comes at a weaker part of the ________, for example at a _______, ________ comes above the earth's surface. • This is called ______ _______. • The movement of these plates goes very slowly. • The _______ of two tectonic plates causes an _________. • The ________ _______ along the bottom of the _______ causes the moving of the tectonic plates. Continental Drift & Tectonic Plates • __________ Hypothesis on Continental Drift • The World’s continents are in ________ • At one time, the continents were ______ together as one… • This was known as _______ • They fit together like a jigsaw puzzle Continental Drift • Wegner’s theory proposed the landmass known as _______ started breaking up • Separated into two parts: ______ and ________ • Wegner’s theory of the separation of Pangea was supported by ______, _________, _________ and _________ evidence Seafloor Spreading • Seafloor is not _________ • Constantly _________ itself • ____ ________ ______ (longest & tallest mountain range in the world, center of the ________ Ocean) • Forms ________: Iceland and Azore • There are _______ in the mountains Plate tectonics • __________ move because they are _________ in plates • The plates shuffle or move _____ of the Earth’s surface • Plates move in _______ _______ and different ______ from each other • There are ______ large plates and several smaller plates Plate Boundaries • _________ Boundaries – Plates move _____from each other – Comes from rock in the ______________ – Partially melted – The rock partially melts = _______ – It was _____ before it left the _______ of the Earth Convergent boundaries • Plates move _______ each other Transform fault boundaries • Plates ______ ______ each other Earthquakes • • • • Devastating ______ (force) applied to _____ Stress causes ______ Eventually the rock cannot bend anymore • It breaks and releases ______ ______ • The released energy ( ______ _____) travel out in all directions Earthquakes cont • The initiating site of the seismic wave: _______ • The point at Earth’s surface directly above the focus: ________ • Measured on a _______ _______ ( the increments are _____ fold in magnitude…) Tsunami • Seismic sea wave • Created by an __________